1. Field of the Invention
This invention relates to the alkoxylation of an active hydrogen-containing compound with an alkylene oxide in the presence of a catalyst.
2. Description of the Prior Art
Alkoxylates are of great importance, for example as intermediates in derivatization processes and as nonionic components in industrial and cosmetic detergents, cleaners and cleansing compositions. They are also employed in a large number of applications as emulsifiers, dispersants and the like. In these applications the desire is frequently for those alkoxylates which exhibit a narrow distribution of the alkoxylation homologs. This distribution is determined essentially by the catalyst used in the alkoxylation reaction.
It was disclosed a long time ago, for example by British Patent 796 508, that antimony pentahalide catalysts lead, in the reaction of compounds containing active hydrogen atoms (for example in the form of hydroxyl groups) with alkylene oxide (for example ethylene oxide and/or propylene oxide), to alkoxylates having a narrow homolog distribution (narrow-range alkoxylates). This advantage is countered by the disadvantage of the difficulty of handling the antimony pentahalides (severe fuming, corrosive, sensitive to hydrolysis) and the unsatisfactory color quality of the alkoxylate.
U.S. Pat. No. 4 996 364 describes unsubstituted polycarboxylic monoesters in the form of alkaline earth metal salts as catalyst for the alkoxylation of compounds containing active hydrogen atoms, such as fatty alcohols. Among the polycarboxylic acids mentioned is succinic acid, although likewise unsubstituted. Although these alkaline earth metal salts of polycarboxylic monoesters possess advantages in comparison to antimony pentahalides as catalyst, they still always leave something to be desired in respect of the homolog distribution and/or appearance of the resulting alkoxylates.
Canadian Patent Application 2 094 556 describes alkali metal or alkaline earth metal salts of alkyl- or alkenylsuccinic monoesters as anticorrosion agents for metalworking, the alkyl or alkenyl substituent containing from 8 to 30 carbon atoms, preferably from 9 to 15 carbon atoms. The document gives no mention or indication in the direction of any other possible application for these half-esters of the substituted succinic acid. It has now been surprisingly found that, when alkaline earth metal salts of alkyl- or alkenylsuccinic half-esters are used as catalyst for alkoxylations, a further improvement is achieved with regard to the narrow homolog distribution and appearance of the resulting alkoxylates.